Research For Ultrasonic Channel Estimation And Equalization Algorithms Based On Linear Frequency Modulation Signal

As the most widely used detection technology, ultrasonic detection is applied in a number of fields such as industrial flaw detection, medical and transportation, due to its nondestructive feature. Linear Frequency Modulation signal is a very important signal for digital signal processing, is often utilized in the ultrasonic detection field. In the practical application, channel is not ideal, so the received data obtained through ultrasonic detection probe has disturbed by probe channel, which makes the received data is not accurate. In order to improving the data accuracy in detection system, it is important to study channel estimation and equalization algorithms, including the application in ultrasonic detection system. Improving the precision of data detection system has important significance. Based on the chirp signal, this paper proposed a new channel estimation and equalization algorithm, which is proved to be effective in both simulation and experiment.This paper firstly study some classical channel equalization algorithms based on LMS algorithm. Besides, this paper put emphasis on discussing a new frequency domain channel estimation algorithm and time delay estimation algorithm based on frequency domain windowing. And these two algorithms are proved to be effective in both theory and simulation. Then this paper discussed different parameters, including step length, iteration times and initial value settings, and their influence on algorithm performance. In addition, this paper discussed the different performance of time delay estimation algorithm based on frequency domain windowing between the original one and when it is combined with the new frequency domain channel estimation algorithm in different SNR environment. The result proves that the new channel estimation algorithm can help. In the last chapter, the new channel estimation algorithm is applied to estimate the characteristics of a ultrasonic detection system.In this paper, the channel estimation and equalization algorithm based on linear frequency modulated signal is proved to be effective in both theory and simulation.